Refrigerating apparatus



Dec. 22,1936. D. D. WlLE 8 REFRIGERAT I NG APPARATUS Filed July 9, 1935INVENTOR T.TO EY Patented Dec. 22, 1936 REFRIGERATING APPARATUS DanielD. Wile, Detroit, Mich assignor to Detroit Lubricator Company, Detroit,Mich, a corporation of Michigan Application July 9, 1935, Serial No.30,440

10 Claims.

My invention relates generally to refrigerating apparatus and moreparticularly to refrigerant evaporators therefor.

In the past, refrigerating systems and particularly refrigeratingsystems having a so-called flooded type of refrigerant evaporator, havenot been entirely satisfactory in operation because of a tendency'of thelubricant of the system to concentrate in the bottom of the evaporator.'The lubricant thus concentrated in the bottom of the evaporator,occupied space which the refrigerant medium should normally occupy andprevented normal transfer of heat to the refrigerant medium with theresult that ebullition of the refrigerant was insuificient, to obtainsatisfactory refrigerating results. In certain types of refrigerantevaporators, the concentration of the lubricant therein is more markedthan in other types and to the extent that the efficiency of the systemis appreciably affected. In some systems, because of the highconcentration of lubricant in the evaporator, it frequently occurs thatthe refrigerant compressor has to operate an abnormally long period oftime before the temperature of the evaporator is decreased to thedesired temperature, which is, of course, ineflicient operation andobjectionable. In addition, when the lubricant concentrates in theevaporator, the compressor is deprived of the benefit of the lubricantand which is also an objectionable condition.

Accordingly, it is an object of my invention to obviate theabove-mentioned objectionable conditions in a refrigerating system;

Another object of my invention is to provide a refrigerating systemhaving a flooded type of evaporator and one which has a substantiallyuniform cycle of operation.

Another object of my invention is to provide for agitating therefrigerant and oil adjacent the bottom-of the evaporator so as toobtain proper ebullition of the refrigerant, and so that the oil willcirculate through the system and to accomplish this in an economicalmanner.

Otherobjects of my invention will become apparent from a reading of thefollowing detailed description in connection with the accompanyingdrawing which forms a part of my specification, and in which drawing-Figure 1 is a diagrammatic view of a refrigerating system embodying myinvention, and

Fig. 2 is a view shown in vertical cross-section of the refrigerantevaporator shown in Fig. 1.

Referring to the drawing by characters of reference, the refrigeratingsystem includes the usual condensing element which may be of anysuitable type and which comprises -a refrigerant compressor l and arefrigerant condenser 2, the compressor being driven by an electricmotor 3. One end of the condenser coil, as at 4, is connected to thecompressor I while the other end is con- 5 nected to a refrigerantreceiver 5. The numeral 6 designates, in general, the cooling element orrefrigerant evaporator and which, in the present instance, is a floodedtype of evaporator. The evaporator 6 includes a header I mounted on thetop thereof, and connected to the header I there is a control deviceflfor controlling the admittance of the refrigerant medium to the headerto maintain the level of the liquid refrigerant therein at apredetermined level. The control device 8 may be a thermostaticexpansion valve or any other suitable control device. A refrigerantsupply line or conduit It) leads from the receiver 5 to the controldevice 8 and through which liquid refrigerant is supplied to theevaporator by the compressor l. A return, or suction line, or conduit Itconnects the header 1 and the compressor I and through which gaseousrefrigerant is withdrawn from the header by the compressor. Thethermostatic control device 8 includes a temperature responsive bulb 9connected thereto by a tube or conduit 9 and which contains a suitablefluid such as methyl chloride, expansible and/or contractible inresponse to changes in temperature. Preferably the bulb 9 is clamped tothe return conduit II and adjacent the outlet end of the evaporator.

' A thermostatic switch means is preferably provided for cutting-in andcutting-out the compressor between predetermined temperature limits, 35and comprises a temperature responsive bulb l2, connected by a conduitI3, to a switch means it. The bulb I2 is preferably clamped to the sidewall of the evaporator in good heat transfer relation therewith andcontains an expansible-contracti- 4 ble fluid, such as methyl chloride.The switch means [4 is connected by lead wires l5 and It to the electricmotor 3, and in-series circuit with the motor 3 and switch l4 there is amanual switch l1.

The evaporator shown in this instance is con- 45 structed of sheet metalforming a top wall ill, a bottom wall I9 and side Walls 20, whichcooperate to provide an enclosed, open end freezing chamber 2| in whichmay be placed the usual trays (not shown) for containing water 50 to befrozen. The evaporator 6 may be formed with two sheets of metal, 22 and23, the inner sheet of which may be flat while the outer sheet of metalmay be formed with a plurality of pressed-out ribs 24 forming, with theadjacent 65 evaporator, the duct means also extend partway across thebottom wall 19 toward the center of the evaporator, as at 21, andterminate in closed ends, and it is in these end portions that lubricanthas a tendency to concentrate and prevent proper ebullition of therefrigerant medium, which condition also exists to a certain degree inother types of evaporators. The refrigerant medium, in liquid form, iscontained in the ducts 25 and in the header I, and when heat is absorbedby the refrigerant, ebullition takes place and the gaseous refrigerantcollects in the upper portion of the header 1.

In order to provide for the proper ebullition of the refrigerant in theevaporator and to do so in an economical manner, I arrange therefrigerant supply conduit ID with a portion 29 thereof so that therefrigerant passing therethrough is in good heat transfer relation withthe refrigerant in the evaporator 6. One or more loops of therefrigerant supply conduit l0 may be arranged beneath the bottom wall IQof the evaporator and may be Welded thereto, or otherwise suitablysecured to the evaporator. If the evaporator is of the type shown,having the duct means 25 terminating along the bottom wall of theevaporator, it is desirable that the portion 29 of the supply conduit 10be arranged adjacent the terminal ends of the duct means, as shown inFig. 2.

A complete operation of the refrigerating system is as follows: Thecompressor I supplies liquid refrigerant through the supply conduit I0and which refrigerant is relatively warm compared to the refrigerant inthe evaporator. As a result, the relatively colder refrigerant in theevaporator absorbs some of the heat of the relatively warmer refrigerantin' the supply line as it passes through the portion 29 of the conduitand which induces ebullition of the refrigerant in the evaporator tooccur. By this arrangement, concentrating of the lubricant in the lowerregions of the duct means 25 is prevented and the lubricant is inducedto vaporize and return to the compressor. After the refrigerant in thesupply line l0 flowsbeneath the evaporator, it is delivered to thethermostatic control device which controls the admission of therefrigerant to the evaporator to maintain the level of the liquidrefrigerant in the evaporator at a predetermined level. Gaseousrefrigerant and vaporized oil is withdrawn from the evaporator header 1through the suction line or return conduit II by the compressor when thetemperature of the evaporator increases above a predeterminedtemperature. The compressor then compresses the gaseous refrigerant anddelivers it to the condenser from whence it passes to the receiver 5, inits liquid form, to be again devlivered to the evaporator and the cyclerepeated.

An advantage of employing 'the relatively warmer refrigerant in thesupply line to agitate the relatively colder refrigerant in theevaporator is that when the refrigerant is admitted to the evaporator,its temperature will be substantially the same as the temperature of therefrigerant in the evaporator with the result that there will becomparatively little gasiflcation of the refrigerant upon its entranceto the evaporator. When refrigerant is admitted to a flooded type ofevaporator and the refrigerant is relatively warmer than the refrigerantin the evaporator, it gasifies immediately upon its entrance into theheader of the evaporator'in accordance with the difference between itstemperature and the temperature of the refrigerant in the evaporator. Asa result, when the valve of the control device opens to admitrefrigerant to a flooded type of evaporator, there is usually a tendencyfor the level of the liquid refrigerant in the evaporator to lowerbecause a large percentage of the compressor capacity is used inwithdrawing the gasified refrigerant from the header, and the loweringof the level of the refrigerant in the evaporator causes the valve toremain open longer than it would normally remain open. Then, when thevalve closes, the entire capacity of the compressor is transferred tothe liquid refrigerant in the evaporator and causes the level thereof torise to the point where the liquid refrigerant overflows into thesuction line. By introducing the refrigerant into the evaporator atsubstantially the same temperature as the refrigerant in the evaporator,it will be seen that theabove objectionable conditions are overcome andthat the system operates much more efficiently.

From the foregoing description it will now be appreciated that I haveprovided a new and improved refrigerating system and one which iseflicient in operation. By agitating the refrigerant medium in theevaporator, lubricant will be prevented from concentrating therein andit will be appreciated that by using the relative- 1y warmer refrigerantin the supply line to cause agitation of the refrigerant in theevaporator, the objectionable conditions in the system are overcome in avery inexpensive manner. In addition, the refrigerant in the supply lineis introduced into the evaporator at substantially the same temperatureas the refrigerant in the evaporator, with the result that the systemoperates much more smoothly than it would if there were a-relativelylarge temperature differential between the temperature of therefrigerant in the evaporator and the temperature of therefrigerantbeing admitted to the evaporator.

What I claim and desire to secure by Letters Patent of the United Statesis:

1. Refrigerating apparatus comprising a refrigerant evaporator, arefrigerant condensing element, a refrigerant supply conduit leadingfrom said refrigerant condensing element to said refrigerant-evaporatorand arranged so that the relatively warmer refrigerant passingtherethrough is in heat transfer relation with the relatively colderrefrigerant in the evaporator so as to induce ebullition of the same,and a return conduit connecting said evaporator and said condensingelement.

2. Refrigerating apparatus comprising a refrigerant evaporator, arefrigerant condensing element, a refrigerant supply conduit connectingsaid evaporator and said condensing element and having a portion thereofintermediate its ends arranged in good thermal contact with said evaP--75 orator whereby the relatively warmer refrigerant vtransfer relationwith the relatively colder refrigpassing through said supply conduitinduces ebullition of the relatively colder refrigerant in saidevaporator, and a refrigerant return conduit connecting said evaporatorand said condensing element.

3. Refrigerating apparatusmomprising arefrigerant evaporator, arefrigerant condensing element, a refrigerant supply conduit connectingsaid evaporator and said condensing element and having an intermediateportion arranged beneath said cooling-element so that therelativelywarmer refrigerant passing through said conduit is' in heattransfer relation with the relatively colder refrigerant in theevaporator whereby to induce vaporization of the refrigerant in theevaporator. and a refrigerant return conduit connecting said evaporatorand said condensing element.

4'. Refrigerating apparatus comprising a refrigerant evaporator, arefrigerant condensing element, a refrigerant supply conduit connectingsaid evaporator and said condensing element and through whichrefrigerant at a relatively higher temperature than the temperature ofthe refrigerant in the evaporator is delivered by the condensing elementto the evaporator, said conduit extending beneath said evaporator and incontact therewith so that the relatively warmer refrigeran't' passingthrough the conduit will heat and induce ebullition of the refrigerantin the evaporator, and a return conduit connecting the said evaporatorand said condensing element 5. Refrigerating apparatus comprising arefrigerant evaporator, a refrigerant condensing element, a refrigerantsupplyconduit connecting said evaporator and said condensing element.said conduit having anintermediate portion between the condensingelementand the evaporator disposed beneath the evaporator along the bottomthereof and in heat transfer relation with the relatively colderrefrigerant in the evaporator so that the relatively warmer refrigerantin said conduit will induce ebullition of the refrigerant erant in saidevaporator to induce ebullition of orator whereby the relatively warmerrefriger ,ant in the supply conduit heats the relatively colderrefrigerant in the evaporator to aid ebullition of the refrigerant inthe evaporator.

8. In a refrigerating system having a flooded type refrigerantevaporator, a condensing element, a return conduit connecting saidevaporator and said condensing element, and a refrigerant supply-conduitconnecting said evaporator and said condensing element and having aportion thereof in heat transfer relation with the evaporator wherebythe relatively warmer refrigerant in the supply conduit heats'the.relatively colder refrigerant in the evaporator to aid ebullition of therefrigerant in the evaporator, and an expansion valve controlling theadmittance of the refrigerant to the evaporator.

9. Refrigerating apparatus comprising a refrigerant evaporator, arefrigerant condenser, a conduit connecting said refrigerant evaporatorand said refrigerant condenser for the passage of a refrigerant medium,said conduit being arranged so that the relatively warm refrigerantmedium passing therethrough is in heat transfer relation with therelatively cold refrigerant medium in the evaporator so as to induceebullition of the refrigerant medium in the evaporator. 10.Refrigerating apparatus comprising a re frigerant evaporator, arefrigerant condenser, a conduit connecting said refrigerant evaporatorand said refrigerant condenser for the passage of a refrigerant medium,a second conduit for the passage of a refrigerant medium, saidsecondnamed conduit having a portion thereof arranged in heat conductingrelation to said refrigerant evaporator so that the relatively warmrefrigerant medium passing through said second-named conduit is in goodheat transfer relation with the relatively cold refrigerant medium inthe evaporator so as to induce ebullition of the refrigerant medium insaid refrigerant evaporator.

' DANIEL D. WILE.

